Evaluate a set of pictures after saving them in Vision Builder AI 3.6

[Cokfat]

Hi,

I'm trying to measure object vibrations. I was thinking about to measure the maximum and the minimum af the amplitude. To realize this I was trying to save at first a set of pictures with the full framerate of the camera. After saving these pictures as *.jpg I was trying to get them in Vision Builder AI with -Simulate Acquisition- to measure a defined number of pictures and evaluate the maximum and minimum amplitude.

This version of my solvement is just working automatically, when I define one filename of my saved in -Simulate Acquisition-.

Is there any way to make this automatically?

Is there any other way of measuring vibrations, acceleration speed of an object?

Thanks a lot.

Cokfat

[Jochen]

Cokfat,

I'm not sure, if machine vision is a good approach for vibration measurements. Typically vibrations are too fast for standard image acquisition systems. Following the Nyquist theoreme your frame rate should be at least twice  the frequency of your vibration signal, but for better amplitude accuracy at reasonable measurement times, the frame rate should be 10 times the vibration frequency.

Typically sensors like accelerometers or microphones are used for vibration analysis.

Here you can find some more information about sound & vibration measurements.

Kind regards,

Jochen Klier

National Instruments

Message Edited by Jochen on 10-31-2008 01:30 PM

[Cokfat]

Thanks a lot Jochen!

I will look after your suggestion for measuring vibrations.

Is there no possibility to save a set of pictures an evaluate them afterwards with Vision Builder AI? (Not depending in measuring vibrations.

Kind Regards

Cokfat

[Jochen]

Cokfat,

you can use the Image Logging function from the Additional Tools palette to save a series of images to disc.

Jochen

[Cokfat]

Hi Jochen,

like I wrote before, I did the Image logging.

When I am using the tool (Simulate Acquisition) to inspect those saved pictures afterwards, I have to select one of those *jpg's manually. In this case, it is not possible to inspect those pictures full automatically.

Is there a solution for this?

Thanks

Cokfat

[Jochen]

Simulate Images allows you to cycle through the images of a folder. This feature is used in most of the VBAI examples. Doesn't this work for you?

[Cokfat]

This works, if you are always using the same pictures.

I will try to explain my steps.

1. state

- using Aquire Image (IEEE 1394) and Image Logging, I am saving a defined amount of pictures in a defined folder. The amount of pictures is limited by the configuration in step Image Logging. To achive more than one pictures, I only found the solution in adding a timestamp to each picture.

After reaching the defined amount of pictures, I am jumping to a second state.

2. state

- using Simulate Acquisition, I have to select one file in a folder to cycle through a folder. Here is my problem.

I tried to use just the path of the folder, without selecting an image to cycle throug the folder. Unfortunately this is not possible. So I must have selected a picture in the selected folder to cycle through it.

Because of of different objects, I have to start the inspection always new. So there will be always different timestamps of an picture.

It would be great, if I could just select an folder an cycle through all the pictures in the folder without selecting an image.

I think it is clearer now.

Cheers

[Elmar_NI]

Hello Cokfat,

with a labview step you are able to choose the path dynamically.
In the attachement you will find a VBAI script.

Kind regards,

 Elmar 

[Cokfat]

Thanks a lot Elmar.

I will try it.

[Cokfat]

Do I need Labview for this?